"But while we have yet to discover a cure for the disease, the situation is not hopeless," says Stuart Richer, O.D., Ph.D., an optometry researcher in Chicago. "Research has shown antioxidants and other compounds in dark-green leafy vegetables may slow the progression of the condition, even among people with advanced cases of it."

What it is

Macular degeneration is a chronic, slowly progressive and painless condition that causes the death of cells in the macula, the small central part of the retina that allows you to see fine detail. It blurs the sharp, central vision needed for activities that require straight-ahead vision, such as reading, sewing, and driving.

There are two types of AMD: wet and dry. Both destroy central vision. Color vision and distance vision also are affected.

Dry AMD, which accounts for the majority of cases of AMD, occurs when cells in the macula begin dying for no apparent reason. The damage causes gradual blurring of the central vision in the affected eye. Often, only one eye is affected; later, the second eye may become involved. The most common symptoms of dry AMD are slightly blurred vision, difficulty recognizing faces, or needing more light for reading. The dry form also can turn suddenly into the wet form; there is no way to tell if or when the dry form will turn into the wet form. Dry AMD usually does not affect peripheral (side) vision.

Wet AMD is more serious than dry AMD and affects about 10 percent of all cases. It occurs when new blood vessels behind the retina start to grow under the macula. New blood vessels are fragile and often leak fluids under the macula. The blood and fluid raise the macula from its normal place at the back of the eye. This damages the macula, causing rapid and significant vision loss. An early symptom of wet AMD is straight lines that appear wavy. Peripheral vision, normally preserved in the dry form of AMD, may be seriously affected in the wet form. Therefore, wet AMD is more likely to lead to total blindness.

See your doctor if you notice any of these symptoms:

A sudden or gradual loss of ability to see clearly, such as difficulty reading fine print or needing more light for reading or doing close work

A decrease in ability to identify colors

Distorted vision, such as wavy lines that should be straight

A dark or empty spot appearing in or near the center of vision

Blurry or fuzzy vision

Difficulty seeing at a distance

Causes and prevention

AMD is most common among people older than 50, but the American Academy of Ophthalmology says it can appear as early as age 40. These factors increase the risk for AMD:

Advancing age -- Individuals over age 75 have a 30 percent chance of developing AMD.

Smoking

Obesity -- Research suggests a link between obesity and the progression of early and intermediate stage AMD to advanced AMD.

Race -- Whites are much more likely to lose vision from AMD than are African Americans.

Family history -- People with a family history of AMD are at higher risk for developing the disease. In some people, AMD may be associated with an immune system response caused by an inherited gene. Genes have been located that are thought to account for about 25 percent of the cases of AMD.

Get regular eye exams. How frequently you should have an eye exam depends on your age and the other risk factors you have for AMD. Your health care provider can help you decide how frequently you should have exams.

Diagnosing AMD

AMD can only be diagnosed with a comprehensive eye exam. This exam should be done by a qualified eye care professional and should include these tests:

Visual acuity test. This uses a standard eye chart with letters of various sizes to test how well you see at various distances.

Dilated eye exam. In this exam, drops are used to dilate the pupils, and the doctor examines your retina and optic nerve. A common sign of AMD are yellow deposits under the retina, called drusen. These deposits can be found during a dilated eye exam.

You may be asked to look at an Amsler grid, which looks like a checkerboard. This grid is used to test for AMD. You look at a black dot in the center of the grid with one eye covered, and repeat with the other eye. If you notice that the straight lines in the pattern appear wavy or appear to be missing while staring at the dot, you may have AMD.

Treating AMD

There is no cure for AMD. Treatment attempts to halt the progression of AMD.

High doses of certain vitamins may slow or halt the vision loss caused by AMD. The Age-Related Eye Disease Study in 2001 indicated that people with moderate to advanced wet or dry AMD reduced their risk for further vision loss by taking high doses of zinc, beta carotene, and vitamins C and E. The supplement combination tested was a daily dose of 500 mg of vitamin C, 400 IU of vitamin E, 15 mg of beta carotene (often as vitamin A; up to 25,000 IU), 80 mg of zinc (as zinc oxide), and 2 mg of copper (as cupric oxide). Talk to your health care provider before taking these supplements, because there may be health risks. If you are a smoker or a former smoker, high doses of beta carotene (vitamin A) may increase your risk for lung cancer. Doses of vitamin E higher than 400 IU have been associated with an increased risk for cardiovascular death.